Innovative methods are critical to the task of examining linkages between urban youths' mental health, their social networks, and their activity spaces (routine locations) in order to understand health behaviors. While drug abuse researchers have begun to address the influence of neighborhood context on substance abuse, our approach is unique in combining neighborhood characteristics with social network and individual characteristics. Unlike previous studies that have focused solely on individuals' home location as a geographic identifier, we incorporate individuals' activity space to yield a richer portrait of exposure to geographic influences. The purpose of this study is to describe and analyze the interactions of three domains: (1) individual domain, (2) social network domain, and (3) geographic domain of two groups of urban adolescents: (a) Non-substance using and (b) Substance abusing, as a first step toward developing a brief, contextually relevant prevention program within primary care settings. This innovative study relies extensively on Geographical Information Systems (GIS) to characterize the activity spaces of the urban adolescents through the analysis of objective social-environmental data hypothesized to influence urban adolescent drug use. These individual, social network, and geographic level factors are used to produce contextually-based risk and protection exposure estimates and to then forecast the odds of membership in one of two aforementioned substance use groups. Specific Aims: Our first aim is broad and illustrative of our primary approach towards understanding complexities of urban substance involvement, while our second aim represents our methodological contribution to the neighborhood health literature. Aim 1: Model the additive and interactive effects of three domains: (1) individual (2) social network, and (3) geographic on the odds of membership in one of two substance use involvement groups: (a) Non-substance Users and (b) Substance Abusers. Aim 2: Examine the influence of geographic characteristics on substance use involvement by comparing subjects' residence location as the sole geographic marker and influence (single point) to that marker PLUS the subjects' activity space data (multiple point). Relevance to Public Health: Our multi-level study will produce rich, highly relevant, ecologically informed prevention data that can guide targeted interventions. Integrated individual, social network and geographical data can serve as a model to direct the development of future innovative substance abuse preventive interventions for urban youth. [unreadable] [unreadable] [unreadable]